Photoelectric Switch

I have a driveway light on a pole that normally in on all night and off during the day. This is controlled by a photoelectric switch. The other day my wife accidentially switched off power to this lamp, now the cycle is reversed, the lamp if off at night and on during the day. Can someome tell me how to reverse this cycle. I have tried to shut the power off and on again, but I still have the same problem. Please help!